Samsung S7 phone, OS updated to most recent version on July 16, 2016. Since then email won't synch, or does so very sporadically. I have 3 accounts set up in the Droid email app: 2 Gmail and 1 Comcast. I saw references on another site about setting the auto synch, in data usage, a certain way. When I go into System>Data Usage the only options I can find are mobile data (on), limited mobile data (off), alert about usage (off), restrict background data (off), show WiFi usage (on), restrict networks (off), show units (GB) and Help. Any suggestions??